Support dynamic loading of policies

[geyslan]

Context: #3209 (comment)

• Introduce policies versioning (map of maps) #3469
  • populateBPFMaps() events_map logic
  • initBPF() ProcessTreeFilter logic
• Remove BPF Map macros (define proper types instead) #3731
• Config policies field need versioning #3805
• Fixes
  • Snapshots Pruning and Inner Map creation rollback
    References:
    • Write to outer map fails due to no wrap around of version in snapshot #4019 (comment)
    • Move PolicyManager into policy pkg #3912
  • Free GetBTFFDByID() resources - Reference
• Refactorings (required)
  • Improve bpf policies config access #3906
  • Invert Policies inner maps key pair #3955
  • chore(policy): add policiesMapByName to Policies #3956
  • Add Iterator generic interface, debut it in Policies #3963
  • chore: make Cloner generic #3966
  • Chore at large #3979
  • chore: refactor equality computation #3997
  • Segregate: Policy, PolicyBuilder, Policies, PoliciesBuilder
  • Create PolicyManager minimal API

    ApplyPolicies(PoliciesBuilder) (Policies, error)
    RemovePolicies(version) error
    GetCurrent() Policies
    Get(version) Policies
    

• ...

[geyslan]

Postponing this since it requires further discussion on how to sync policies in bpf and userland.

[yanivagman]

@geyslan I thought about the following API to be added:

AddPolicy(Policy) error
UpdatePolicy(Policy) error
DeletePolicy(Policy) error
ListPolicies()

WDYT?

[geyslan]

@yanivagman considering that this API should be to PolicyManager, perhaps:

DeletePolicy(name) error

instead of the policyObject as parameter.

[yanivagman]

@yanivagman considering that this API should be to PolicyManager, perhaps:

DeletePolicy(name) error

instead of the policyObject as parameter.

Yes, I agree.
Getting into more details:
AddPolicy(policy) error - Add a new policy to Tracee. A full policy (struct parsed from the yaml) is provided. If a policy with the same name already exists, an error should be returned.
UpdatePolicy(policy) error - for now, we won't support providing deltas in the update, and full description of the new policy (as a struct) must be provided. We should decide what to do in case a policy with the same name doesn't exist. We can either return an error or simply add the new policy.
DeletePolicy(name) error
ListPolicies() policies

WDYT?